CN110418999B

CN110418999B - Apparatus and method for determining repair shape for processing defect of lithography mask

Info

Publication number: CN110418999B
Application number: CN201880016925.1A
Authority: CN
Inventors: J.奥斯特; M.韦布林杰
Original assignee: Carl Zeiss SMT GmbH
Current assignee: Carl Zeiss SMT GmbH
Priority date: 2017-03-08
Filing date: 2018-02-27
Publication date: 2022-10-14
Anticipated expiration: 2038-02-27
Also published as: KR20190119656A; TW201842401A; KR102327126B1; US11079674B2; WO2018162281A1; CN110418999A; TWI731227B; DE102017203841A1; US20190391482A1

Abstract

The invention relates to a method for determining a repair shape (195) for processing at least one defect (140) of a lithography mask (100), comprising the steps of: (a) Determining at least one correction value (185) for a repair shape (195) of the at least one defect (140), wherein the correction value (185) takes into account a position (175) of at least one pattern element (130) of the lithographic mask (100), the at least one pattern element not contacting the at least one defect (140); and (b) correcting the repair shape (195) by applying at least one correction value (185).

Description

Apparatus and method for determining repair shape for processing defect of lithography mask

Cross Reference to Related Applications

The present application claims the benefit of german patent application No. 10 2017 203 841.1, filed on 3, 8, 2017, entitled "Verfahren und vorticihtung zum Ermitteln einer repaarturform zum bearbeitenen eines deffekts einer photoraphischen mask" and the entire contents of which are incorporated herein by reference.

Technical Field

The present invention relates to a method and apparatus for determining a repair shape for processing a defect of a lithographic mask.

Background

Due to the ever-increasing integration density in the semiconductor industry, photolithographic masks are required to image smaller and smaller structures. Thus, the production of photomasks has become more complex and therefore more expensive. The reduction in the size of the photomask structure results in new, additional errors or defects on the photomask. The added expense and resultant cost pressure during the manufacture of smaller structure photomasks will force the repair of defects that occur during mask production or during use of the mask to avoid its expensive, fully updated production.

Before repairing a defect on a photomask, the defect needs to be located. This is achieved by optical inspection, which preferably uses short wavelength photons. In the second step, the local defects are analyzed by scanning using a particle beam (ions or electrons) from a FIB (focused ion beam) scanning microscope or a Scanning Electron Microscope (SEM). If an electron beam is used, the backscattered and secondary electrons released from the electrons of the photomask surface to be inspected are used to generate an image of the photomask surface. If a focused ion beam is used, it is analyzed for its mass (SIMS, secondary ion mass spectrometry) and the secondary ions (other than secondary electrons) released from the ions at the substrate surface will image the composition of the irradiated surface.

U.S. patent No. US 8 316 698 B2 describes difficulties that may occur when analyzing defects of pattern elements adjacent to a photomask. The defect analysis provides a repair shape for the discovered defects. The repair shape defines a projection of the identified defect onto the substrate surface of the photomask. Here, the projection is performed perpendicular to the substrate surface of the lithographic mask.

The identified defects of the lithography mask are preferably corrected by a particle beam induced procedure. Defects that arise due to the presence of material at points on the mask substrate that should be transparent (so-called opaque defects) will generally be corrected by means of a particle beam induced etching procedure. Defects that represent points lacking absorbing pattern material (so-called transparent defects) are preferably corrected by a particle beam induced deposition procedure. These particle beam induced etch and deposition processes are strongly localized processes. Ideally, these local processing procedures are limited to the beam diameter over the defect or repair shape. However, in a mathematical sense, the beam cannot be focused on a spot-like diameter. Furthermore, the particle beam induction process is not localized at the focal point of the particle beam due to the movement of the molecules of the etching or deposition gas.

In addition to the required defect correction, the repair or correction of defects of a lithography mask, which is effected solely on the basis of the repair shape, may thus also lead to damage of the substrate of the photomask surrounding the defects. In addition, repairing defects of adjacent pattern elements may also affect such pattern elements.

This problem has been identified. Thus, ebeam Initiative,20 April 2015 in Yokohama-Japan (www, ebeam, org/docs/ebeam-initial-dimensions pfd), published by the applicant, describes a low energy electron beam suitable for repairing small defects independently located on a photomask substrate, which is substantially based on a repair shape without correcting the repair shape, wherein the area of the mask substrate damaged by the e-beam induced etching process is small.

Chapter 4 "Ion Beam Technologies" in "Beam Processing Technologies" edited by N.G. Einstpruch, S.S. Cohen, and R.N. Singh, in VLSI Electronics microscopy services, volume 21, academic Press, the author L.R. Harriot describes the practice of scanning an Ion Beam over a defect to remove the defect, with the Ion Beam being at a Beam diameter distance from the edge of the defect.

US patent document No. US 6 591 154 B2 explains a method of maintaining a distance from the defect edge when correcting a defect on a wafer or mask. For this purpose, the operator of the repair device draws a polygon around the defect to be corrected. The distance of the ion beam or laser beam from the defect edge is set by the line width of the polygon and thus the repair shape of the defect is adjusted or corrected (deviated).

In the cited document, the correction value or adaptation value (deviation) is used to adjust the entire repair shape of the defect, or at least a portion of the repair shape adjoining the mask substrate or pattern element, to accommodate the subsequent correction procedure. This method of adjusting the repair shapes is no longer satisfactory for future masks due to the reduced size of the structure or pattern elements of the photomask.

It is therefore an object of the present invention to specify a method and a device for determining repair shapes for defects of a lithography mask, which at least partially avoid the above-mentioned disadvantages when determining repair shapes.

Disclosure of Invention

According to an exemplary embodiment of the present invention, this problem is solved by the method described below. In one embodiment, a method for determining a repair shape for processing at least one defect of a lithographic mask includes the steps of: (a) Determining at least one correction value for a repair shape of the at least one defect, wherein the correction value takes into account a position of at least one pattern element of the lithographic mask, the at least one pattern element not contacting the at least one defect; and (b) correcting the repair shape by applying at least one correction value.

Thus, the method according to the invention takes into account not only one or more pattern elements of the photomask that border the defect, but also pattern elements that are located in the vicinity of the defect. The method according to the invention does not involve additional outlay on the apparatus, since a particle beam device is required in any case for locating and processing the defects. The expression "in the vicinity of a defect" relates to the distance of the pattern element from the defect, which is only so small that the pattern element is located at least partially in the processing region of the defect during the processing procedure of the defect, as a result of which it may be modified by the processing procedure. The expression in the vicinity of the defect depends on the device capabilities of the defect handling apparatus in question.

According to another exemplary embodiment, the problem indicated in the foregoing is solved by a method as described below. In one embodiment, a method for determining a repair shape for at least one defect of a processing lithography mask comprises the steps of: (a) Determining at least one correction value for a repair shape of the at least one defect, wherein the correction value takes into account a lateral extent of the at least one defect on the substrate surface of the lithographic mask; and (b) correcting the repair shape by applying at least one correction value.

The method according to the invention will take into account the lateral extent of the defect when deciding on the correction value for the repair shape of the defect. Therefore, the cost of the defect processing program or the defect correction program will be considered in correcting the repair shape. Therefore, the duration of the defect handling procedure will be considered, as the surroundings of the defect may be affected during at least some of this period. The method according to the invention therefore goes beyond the correction of the repair shape, in which the edges of the defect are reduced by a predetermined amount, depending on whether the defect adjoins a pattern element or ends up on the substrate of the mask.

In the present application, the expression "lateral extent" describes the projection of defects onto the plane of the undisturbed surface of the substrate forming the lithographic mask. Here, the projection is performed substantially perpendicular to the surface of the substrate.

In the present application, the expression "substantially" describes the measured variable within the error specification if a measuring device according to the prior art is used.

According to another exemplary embodiment, the problem explained above is solved by a method as described below. In one embodiment, a method for determining a repair shape for processing at least one defect of a lithographic mask includes the steps of: (a) Determining at least one correction value for a repair shape of the at least one defect, wherein the correction value takes into account a form of at least one pattern element of the lithographic mask, the at least one pattern element contacting the at least one defect; and (b) correcting the repair shape by applying at least one correction value.

The method according to the invention takes into account not only the boundaries of the defect and the pattern elements, but also the shape of the common boundaries of the defect and the pattern elements, by means of constant correction values for the repair shape. This is particularly advantageous because the particle beam of a scanning particle beam microscope will cause an increase in secondary electron emission or secondary ion emission at the edges of the pattern elements during repair of the defect; this may result, for example, in a so-called "riverbed". The correction of the repair shape thus determined with the aid of the method according to the invention is far beyond the prior art.

The at least one correction value may take into account a lateral dimension of the at least one pattern element.

Treating defects that are adjacent to pattern elements represents a compromise between the degree of correction of defects along the boundary and the degree of damage to adjacent pattern elements. By considering the lateral dimensions of the pattern elements along the common boundary, it is possible to optimize this compromise locally.

In the present application, the expression "lateral dimension of a pattern element" denotes the extent of the pattern element in a plane parallel to the substrate surface of the lithographic mask.

The at least one correction value may take into account at least one rotation angle of at least one pattern element.

In addition to the lateral dimensions of the pattern elements adjoining the defect, the correction of the repair shape can likewise take into account details occurring at the corners of the pattern elements.

The at least one correction value may result in a decrease of the repair shape near the at least one corner of the at least one pattern element compared to the correction value near the straight line region of the pattern element if the corner protrudes into the at least one defect, and/or the at least one correction value may result in an increase of the repair shape near the at least one corner of the at least one pattern element compared to the correction value near the straight line region of the at least one pattern element if the at least one defect protrudes into the corner of the at least one pattern element.

The at least one correction value may take into account a lateral dimension of the at least one pattern element and at least one corner of the at least one pattern element.

Determining at least one correction value may further comprise: the thickness and/or material composition of at least one pattern element is taken into account.

The thickness of the pattern elements having a common boundary with the defect has an effect on the defect handling procedure for removing the defect. The material composition of the pattern elements affects the degree of damage sustained by the pattern elements during the defect correction procedure. The method described herein is advantageous in considering this aspect when correcting the repair shape in order to find the best possible compromise between defect correction and variation of the pattern elements along the common boundary.

Determining at least one correction value may further comprise: the thickness and/or material composition of the at least one defect is taken into account.

The thickness and the material composition have a decisive influence on the costs required for removing the defects. By including these parameters in the correction values for the repair shape, the repair procedure for the defect will be optimized while minimizing damage to the photomask.

Treating the at least one defect may include: a particle beam induced etching procedure and/or a particle beam induced deposition procedure is performed on the corrected repair shape of the at least one defect.

Defects in the form of excess material, such as excess absorber material of pattern elements (so-called opaque defects) are typically treated by a particle beam induced etching procedure. For example, a particle beam induced etching process may be corrected using an electron beam and one or more etching gases provided locally at the incident location of the electron beam. For example, the etching gas may comprise xenon difluoride (XeF 2), a halogen, and/or a halogen-containing gas.

Defects in the form of missing material (e.g. absorber material lacking pattern elements), so-called transparent defects, are usually corrected by particle beam induced deposition procedures. For example, a particle beam induced deposition process may be corrected using an electron beam and one or more deposition gases provided locally at the incident location of the electron beam. Hexacarbonyl chromium (Cr (CO) ₆ ) Is an example of a deposition gas.

Determining the at least one correction value may include approximating the at least one correction value on an empirical basis. For this reason, the defects to be analyzed are preferably assigned to different classes of defects with different parameters. Based on the number of advances of the defect handling operation, it is possible to update the category of the defect and its parameter set.

Determining the at least one correction value may include analyzing the test mask.

Applying at least one correction value may include: the area of the repair shape is reduced by correcting at least one portion of the edge of the repair shape.

Thus, the outer contour of the repair shape is locally adapted to the defect itself and to the surroundings of the defect. Here, not only the surroundings of the adjoining defects but also the surroundings of the defects located in the interaction region of the processing program are taken into account.

Determining the at least one correction value may comprise determining the at least one correction value as described in connection with the preceding embodiments 2 and 3.

Determining the at least one correction value may comprise determining the at least one correction value as described in connection with embodiments 1 and 2.

Combining at least one correction value from both embodiments may comprise a linear combination.

Determining at least one correction value may include: averaging at least one portion of the edge of the at least one defect that does not contact the at least one pattern element; and determining a perpendicular to a tangent to the average edge of the at least one defect to determine a distance between the average edge and the at least one pattern element not contacting the at least one defect and a lateral extent of the at least one defect on the surface of the substrate.

Determining at least one correction value may include: a perpendicular line is formed in a region of the at least one pattern element contacting the at least one defect for determining a lateral extent of the at least one defect and a lateral extent of the at least one pattern element contacting the at least one defect.

The computer program may comprise instructions which, when executed by a computer system, cause the computer system to perform the method steps of the aspects explained hereinbefore.

In an exemplary embodiment, an apparatus for determining a repair shape for processing at least one defect of a lithography mask has: (a) a measurement unit implemented to determine a repair shape; (b) A calculation unit implemented to decide at least one correction value for a repair shape of at least one defect, wherein: (i) The at least one correction value takes into account a position of at least one pattern element of the lithographic mask, the at least one pattern element not contacting the at least one defect; (ii) The at least one correction value takes into account a lateral extent of the at least one defect on the substrate surface of the lithographic mask; and/or (iii) the at least one correction value takes into account a form of at least one pattern element of the lithographic mask, the at least one pattern element contacting the at least one defect; and wherein (c) the calculation unit is further operative to correct the repair shape by applying at least one correction value.

The apparatus may be implemented to perform the method steps of the foregoing aspects.

Drawings

The following detailed description will describe presently preferred exemplary embodiments of the invention with reference to the drawings, in which:

the right half of fig. 1 depicts the correction of the repair shape of a defect of a lithography mask according to the prior art, and the left half schematically shows the correction of the repair shape according to two of the methods described in the present application;

FIG. 2 schematically shows correction values for a repair shape for a defect adjacent to a pattern element, wherein lateral dimensions of the defect and the pattern element vary perpendicular to a boundary line of the defect and the pattern element;

FIG. 3 schematically indicates corrected values for a repair shape in which a pattern element has two corners in the region where a defect contacts the pattern element;

FIG. 4 reproduces a schematic diagram of a test structure for determining correction values for repair shapes of test defects, wherein the test defects are adjacent to pattern elements, have a stepped lateral dimension, and are at a distance from different pattern elements;

FIG. 5 shows the test structure of FIG. 4 after removal of the test defect; and

FIG. 6 shows a flow chart of a method for determining repair shapes for defects of a processing lithography mask.

Detailed Description

Preferred embodiments of the method according to the invention and of the device according to the invention will be explained in more detail below. However, the method according to the invention is not limited to the exemplary application explained below. Rather, the methods described herein may be used to determine the repair shape of defects that may be present in all types of photomasks. Further, the method described in the present application is not limited to correcting defects of a photomask. Rather, these methods and corresponding apparatus may also be used, for example, to determine repair shapes for integrated circuit defects.

The right half of fig. 1 (i.e. to the right of vertical line 142) shows the correction of the repair shape according to the prior art. Mask 100 includes a substrate 110 and

pattern elements

120 and 130. In the example of fig. 1, photomask 100 is a transmissive mask. The substrate 110 of the mask 100 typically comprises quartz.

Pattern elements

120 and 130 substantially completely absorb optical radiation in the actinic wavelength range of the photolithographic mask. The

pattern elements

120 and 130 contain an absorber of chromium or opaque MoSiON-based (molybdenum silicon oxynitride) as an absorber material. The method for determining the correction value for the repair shape described below can be used for all types of photo masks 100, including masks for the Extreme Ultraviolet (EUV) wavelength range and so-called NIL masks (i.e. masks for nanoimprint technology (not shown in fig. 1)).

Mask 100 has a defect 140 adjacent pattern element 120. For example, the defect 140 may include an excess of absorber material (an opaque defect). If this applies, defect 140 may have substantially the same height as

pattern elements

120, 130. However, the opaque defects 140 may have any height. It is also possible for the defect to have a different material or a different material composition than the

pattern elements

120, 130. In addition, defect 140 may also be a defect that lacks absorber material (a transparent defect; not shown in FIG. 1). In addition, defects 140 may include excess or missing substrate material (also not shown in FIG. 1).

Preferably, an inspection tool is used to detect defect 140 and a scanning particle beam microscope (typically a scanning electron microscope) is used to analyze defect 140. Next, the defect locations are compared to non-defective locations of photomask 100, which have the same pattern structure as the locations plagued by the defects. Alternatively, the defect locations may be compared to the design data for the defect mask segments. Repair shape 145 of defect 140 is obtained by subtracting a non-defective mask segment from a segment having a defect. Thus, repair shape 145 is a projection of defect 140 onto the surface plane of substrate 110 of mask 100. In this representation, the image of the repair shape contains only the defect itself, without the

pattern elements

120 and 130 of the corresponding mask segments. However, for purposes of illustration,

pattern elements

120 and 130 are reproduced in the exemplary representation of FIG. 1 and in subsequent figures. The calculation unit of the scanning particle beam microscope may be used to determine the repair shape 145 of the defect 140.

As explained in the introductory portion of the description, processing defect 140 based on repair shape 145 will result in a comprehensive correction of defect 140. However, due to the lateral extent of the processing region, defect processing may damage the substrate 110 of the mask 100 and the pattern elements 120 adjacent to the defect 140. Furthermore, processing defect 140 may modify pattern element 130, which does not have a common boundary with defect 140, but is positioned at least partially near defect 140.

Thus, the repair shape 145 of the defect 140 is corrected in the prior art. This is accomplished by first correcting repair shape 145 of defect 140 a fixed distance 157 along the boundary of defect 140 relative to surrounding substrate 110 so that the corrected repair shape has a new boundary 155 along substrate 110. This correction of the repair shape 145 is also referred to as edge deviation.

Repair shape 145 is also corrected by a fixed value 162 along the common edge of defect 140 and pattern element 120 so that the corrected repair shape has a new edge 160 along pattern element 120. This correction of the repair shape 145 is also indicated as a volume deviation. The volume deviation and the edge deviation may have the

same distances

157 and 162. However, distances 157 and 162 are typically different correction values for the repair shape 145. The repair shape 145 of the defect 140 therefore has two correction values, with the aid of which the entire outer contour of the repair shape 145 of the defect 140 is corrected.

The left half of fig. 1 shows mask 100 and the mask segments of defect 140, which are axially mirrored at vertical line 142. This left half is now used to explain portions of the method described in this application for determining the correction values for repair shape 145 of defect 140. In a first step, a tangent to edge 162 is determined at a predetermined point 165 of repair shape 145 or defect 140 adjacent substrate 110. If defect 140 does not have a smooth edge 162 (unlike that shown in FIG. 1), then a predetermined portion of edge 162 is averaged prior to determining the tangent.

Thus, a perpendicular line 170 is drawn perpendicular to the tangent line and determines its intersection with

pattern elements

120 and 130. Even if pattern element 130 is not in direct contact with repair shape 145 of defect 140, distance a of point 165 of edge 162 is considered in determining the correction value for repair shape 145 _i 175. Here, the local correction value C _i 185 are determined by the pattern element 130 meeting the edge 162 of the repair shape 145 at point 165Distance a from _i 175：

C _i ＝f ₁ (a _i ) (1)

Function f ₁ The distance a from the pattern element 130 may be considered in a non-linear manner _i . However, to a first approximation, f ₁ Is a distance a _i Is a linear function of (a). In addition, correction value C _i A constant correction contribution may be included, however its equation (1) is omitted. For the accuracy of the correction value 185, apart from the distance a to the pattern element 130 _i In addition, distance b between point 165 of edge 162 of shape 145 and pattern element 120 (which is in contact with defect 140) is to be repaired _i 180 are also considered advantageous. This is particularly important at points of repair shape 145 where the lateral dimension 180 of defect 140 is small (and thus the lateral dimension of repair shape 145 is also small). Thus, equation (1) is extended to:

C _i ＝f ₁ (a _i )+f ₂ (b _i ) (2)

unlike the prior art, equation (2) describes the locally spatially correlated correction values 185 for the defect 140. The correction value 185 of equation (2) may be supplemented by a continuous curve 190. In the example shown in FIG. 1, the correction values 185 and/or the closed curve 190 are used to generate a corrected repair shape 195.

It is also possible to consider only the lateral extent of defect 140 (i.e., based on f) ₂ (b _i ) And neglects the effect of the defect handler on pattern elements 130 to determine the correction value for defect 140.

Similar to fig. 1, fig. 2 shows a section of the mask 100. This example applies to a discussion of a portion of the repair shape that determines defect 240 along the common boundary of pattern element 220 and defect 240. Fig. 2 shows the left half of fig. 1, but with two differences. First, defect 240 has a different shape at the left edge than defect 140 of FIG. 1. Second, pattern element 220 has a different shape from pattern element 120 of fig. 1.

To determine the correction value for the repair shape, a perpendicular line 270 perpendicular to the edge 250 of the pattern element 220 is determined at a different point 265 of the edge 250. Distance d _i 275 describes

edges

262 and 262 of defect 240The distance between defect 240 and point 265 of common edge 262 of pattern element 220. Distance e _i 280 denotes the distance between the edge 230 of the trailing end of the pattern element 220 and the point 265 of the defect 240 and the common edge 250 of the pattern element 220. Based on these definitions, it is possible to introduce a correction value K _i 285, which takes into account the local lateral extent of both the defect 240 and the pattern element 220:

K _i ＝f ₃ (d _i )+f ₄ (e _i ) (3)

correction K at point 265 along common edge 250 of defect 240 and pattern element 220 _i 285 may again be supplemented by the formation of a continuous line 290. Correction K along the line of contact between defect 240 and pattern element 220 _i 285, and 290 are part of a repair shape 295 for defect 240. Equation f, as explained in the discussion regarding equation (1) ₃ And f ₄ The distance d of the defect 240 may be considered in a non-linear manner _i And the lateral dimension e of the pattern element 220 _i . However, to a first approximation, will f ₃ And f ₄ Considered as the transverse dimension d _i And e _i Is usually sufficient.

As long as the dimension d _i 275 and e _i 280 is much larger than the diameter of the processing region of the defect handling process and a single correction value is sufficient to correct the repair shape of the defect 240 in this region of the common boundary line. This situation is shown at the right edge in fig. 2. In this limited case, the correction of the prosthetic shape 295 discussed herein is incorporated into the previous correction for the volume deviation.

In the central image area of fig. 2, the defect 240 is only adjacent to a narrow web 255 of pattern elements 220. Correction value K _i 285 are significantly increased in this area to avoid irreparable damage to pattern elements 220 in the area of narrow web 255 when processing defect 240. This means that the distance e is small _i And a function f ₄ Determining a correction value K in the area of the narrow web 255 of the pattern elements 220 _i 285, and therefore the repair shape 295.

In the image edge region on the left side of fig. 2, first, the cross of the pattern element 220To dimension e _i 280 is significantly smaller than the right-hand portion of fig. 2. Second, the lateral dimension d of the defect 240 _i 275 in this region. Therefore, correction value K _i 285 depends on the function f of equation (3) in this part of the common boundary of the pattern element 220 and the defect 240 ₃ And f ₄ 。

Based on the correction value 195 of fig. 1 (i.e., the aforementioned edge deviation) along the substrate 110 of the lithographic mask 100 and based on the correction value 295 of fig. 2 (i.e., the aforementioned volume deviation) along the region where the defect 240 contacts the pattern element 220, it is possible to determine a corrected repair shape for the defect that takes into account the lateral dimensions of the

defects

140, 240 and the lateral dimensions of the

pattern elements

120, 220 adjacent to the

defects

140, 240 and the distance of the pattern element 130 that is not in contact with the defect 140.

Fig. 3 illustrates, in an exemplary manner, the correction of the repair shape of a pattern element in contact with a defect in an area where the pattern element has a corner. Fig. 3 shows an enlarged view of the left partial image of fig. 1 at the corners of pattern element 120 and the area of defect 140 adjacent to pattern element 120. Furthermore, fig. 3 shows a correction according to the prior art. Curve 160 is along a common boundary 330 of pattern element 120 and defect 140 at a fixed distance 162. Corner P of pattern element 120 ₁ And P ₂ Is mapped to a corner P by a curve 160 ₁ ' and P ₂ ’。

The curve 385 of fig. 3 shows that two corners P are considered when determining the correction value for the repair shape ₁ And P ₂ The outline of the correction value 385 of the repair shape 395 in the case of a defect handling problem in the area of (b). In the example shown in fig. 3, an elliptic function is used to determine two rotation angles P ₁ And P ₂ The correction value in the region of (a). Corner P _n Angle alpha of _n As a parameter. The rotation angle P is measured in the region of the defect 140 (i.e. outside the pattern element 120) _n Angle alpha of _n . As can be seen from FIG. 3, the angle 1 ≦ α compared to the prior art correction values _n The angle is 179 DEG or less to produce a reduced portion of the ellipse. In contrast, the range of 181 degrees is less than or equal to alpha _n An angle of 359 ° or less compared with the correction values of the prior art yieldsAn increasing portion of an ellipse. For alpha ₁ =270 ° and α ₂ =90 °, the parameters of the decreasing elliptical portion and the increasing elliptical portion are identical in the first approximation. The parameters characterizing the elliptical portion are determined experimentally.

Equation (3) describing the volume deviation (i.e., correction of the repair shape 295 of the defect 140 adjacent to the pattern element 120) is extended by corner correction:

K _i ′＝K _i +f ₅ (α _n ) (4)

wherein K is _i The correction value of equation (3) is expressed.

The curve that correctly determines the repair shape 395 of the defect 140 along the common boundary line 330 or the edge 330 of the pattern element 120 is important to repair the defect 140. The particle beam used to repair defect 140 may have an increased secondary electron emission rate in the region of edge 330, which may cause a so-called "riverbed" when incident on substrate 110 of the lithography mask.

By using correction values C _i 190 and K _i 290 or K _i ' the

repair shape

195, 295 of the

defect

140, 240 can be corrected to the best possible extent without significantly damaging the substrate 110 or the

pattern element

120, 130, 220.

The diagram 400 in fig. 4 schematically shows the correction value C for determining equation (2) _i And the correction value K of equation (3) _i Test structure 410. The test structure 410 comprises two

pattern elements

420 and 430 and a test defect 440 made of an absorbing material, which is deposited on the substrate 110 of the test structure 410 in the form specified in fig. 4. Test defect 440 adjoins pattern element 430 and has a lateral dimension 475 that increases from left to right in a stair step fashion until test defect 440 contacts pattern element 420 at the last step at the right edge of fig. 4. The test defect 440 produces a repair shape 445. The test defect 440 is removed from the substrate 110 of the test structure 410 with the aid of a particle beam induced etching procedure. Here, the handler for testing defect 440 is based on uncorrected repair shape 445.

Schematic diagram 500 in FIG. 5 showsThe test structure 410 of fig. 4 is shown after etching the test defect 440 based on the uncorrected repair shape 445. Here, only the effect of the particle beam induced etch process on

pattern elements

420 and 430 of test structure 410 is considered. The adverse effects of the process of testing for defects 440 on the substrate 110 of the test structure remain unaccounted for. The etching process of the uncorrected repair shape 445 extends beyond the repair shape due to the non-point-like processing region. This means that

pattern elements

520 and 530 are also removed in the particle beam induced etching process in the area where test defect 440 is near

pattern elements

520 and 530 or where test defect 440 contacts a portion of

pattern elements

520 and 530, as compared to edge 550 of

original pattern elements

420 and 430. Correction value C of equation (2) _i May be determined from the removed

portions

540 and 545 or the

deviations

540 and 545 from the

original pattern elements

420 and 430.

Pattern elements

520 and 530 in fig. 5 illustrate the dependence of the process on the lateral dimensions of the test defect 440 by

deviations

540 and 545 from the

original pattern elements

420 and 430. Correction value K of equation (3) _i The decision may be based on the process induced

deviations

540 and 545 of the

pattern elements

520 and 530.

Flow chart 600 in FIG. 6 shows a method for determining a repair shape for a defect of a processing lithography mask. The method begins at step 610. In a second step 620, at least one correction value of the repair shape of at least one defect is determined, wherein:

(i) The correction value takes into account a position of at least one pattern element of the lithographic mask, the at least one pattern element not contacting the at least one defect;

(ii) The correction value takes into account a lateral extent of the at least one defect on the substrate surface of the lithographic mask; and/or

(iii) The correction value takes into account the form of at least one pattern element of the lithographic mask, which at least one pattern element contacts the at least one defect.

In a next step 630, the repair shape is corrected by applying at least one correction value. The method finally ends at step 640.

Claims

1. A method for determining a repair shape (195) for processing at least one defect (140) of a lithography mask (100), wherein the method comprises the steps of:

a. determining at least two locally spatially dependent correction values (185) of a repair shape (195) of the at least one defect (140), wherein the at least two locally spatially dependent correction values are different values, the at least two locally spatially dependent correction values (185) taking into account a position (175) of at least one pattern element (130) of the lithographic mask (100), the at least one pattern element not contacting the at least one defect (140); and

b. the repair shape (195) is corrected by applying the at least two locally spatially correlated correction values (185).

2. A method for determining a repair shape (195) for processing at least one defect (140) of a lithography mask (100), wherein the method comprises the steps of:

a. determining at least two locally spatially dependent correction values (185) of a repair shape (195) of the at least one defect (140), wherein the at least two locally spatially dependent correction values are different values, the at least two locally spatially dependent correction values (185) taking into account a lateral extent (180) of the at least one defect (140) on a surface of a substrate (110) of the lithographic mask (100); and

3. A method for determining a repair shape (295) for processing at least one defect (240) of a lithography mask (100), wherein the method comprises the steps of:

a. determining at least two locally spatially dependent correction values (285, 385) of a repair shape (295, 395) of the at least one defect (240), wherein the at least two locally spatially dependent correction values are different values, the at least two locally spatially dependent correction values (285, 385) taking into account a form of at least one pattern element (220) of the lithographic mask (100), the at least one pattern element contacting the at least one defect (140, 240); and

b. the repair shape (295) is corrected by applying the at least two locally spatially correlated correction values (285, 385).

4. The method of claim 3, wherein the at least two locally spatially dependent correction values (285) take into account a lateral dimension (280) of the at least one pattern element (220).

5. The method of claim 3, wherein the at least two locally spatially dependent correction values (385) take into account at least one corner (340, 350) of the at least one pattern element (220).

6. The method of claim 5, wherein the at least two locally spatially dependent correction values (385) result in a reduction of the repair shape (395) in the vicinity of the at least one corner (350) of the at least one pattern element (120) compared to correction values in the vicinity of a straight-line region of the pattern element (120) if the corner (350) protrudes into the at least one defect (140), and/or wherein the at least two locally spatially dependent correction values (385) result in an increase of the repair shape (395) in the vicinity of the at least one corner (340) of the at least one pattern element (120) compared to correction values in the vicinity of a straight-line region of the pattern element (120) if the at least one defect (140) protrudes into the corner (340) of the at least one pattern element (120).

7. The method of claim 4 or 5, wherein the at least two locally spatially dependent correction values (285, 385) take into account a lateral dimension (280) of the at least one pattern element (220) and at least one corner (340, 350) of the at least one pattern element (120, 220).

8. The method of one of claims 1 to 6, wherein determining the at least two locally spatially correlated correction values (185, 285, 385) further comprises: the thickness and/or the material composition of the at least one pattern element (120, 130, 220) is taken into account.

9. The method of any of claims 1 to 6, wherein determining the at least two locally spatially correlated correction values (185, 285, 385) further comprises: the thickness and/or material composition of the at least one defect (140, 240) is considered.

10. The method of any of claims 1 to 6, wherein processing the at least one defect (140, 240) comprises: a particle beam induced etching procedure and/or a particle beam induced deposition procedure is performed on the corrected repair shape (195, 295, 395) of the at least one defect (140, 240).

11. The method of any of claims 1 to 6, wherein determining the at least two locally spatially correlated correction values (185, 285, 385) comprises analyzing a test mask (410, 610).

12. The method of any of claims 1 to 6, wherein applying the at least two locally spatially correlated correction values (185, 285, 385) comprises: the area of the repair shape (195, 295, 395) is reduced by correcting at least a portion of the edges of the repair shape (195, 295, 395).

13. The method of any one of claims 1 to 6, wherein determining the at least two locally spatially correlated correction values (185, 285, 385) comprises combining the at least two locally spatially correlated correction values (185, 285, 385) of claims 2 and 3.

14. The method of any of claims 1 to 6, wherein determining the at least two locally spatially correlated correction values (185, 285, 385) comprises combining the at least two locally spatially correlated correction values (185) of claims 1 and 2.

15. The method of claim 13, wherein combining at least two locally spatially correlated correction values (185, 285, 385) of both claims comprises linear combining.

16. The method of claim 14, wherein combining at least two locally spatially correlated correction values of two claims comprises linear combination.

17. The method of claim 1 or 2, wherein determining the at least two locally spatially correlated correction values (185, 285, 385) comprises: averaging at least a portion of an edge (162) of the at least one defect (140) that does not contact the at least one pattern element (130); and determining a perpendicular to a tangent to an average edge of the at least one defect (140) to determine a distance (175) between the average edge and at least one pattern element (130) not contacting the at least one defect and a lateral extent (180) of the at least one defect (140) on the surface of the substrate (110).

18. The method of claim 2 or 3, wherein determining the at least two locally spatially correlated correction values (185, 285, 385) comprises: a perpendicular is formed in a region of the at least one pattern element (120, 220) contacting the at least one defect (140, 240) for determining a lateral extent (180, 270) of the at least one defect (140, 240) and a lateral extent (180, 270) of the at least one pattern element (120, 220) contacting the at least one defect (140, 240).

19. A computer readable storage medium comprising a program containing instructions which, when executed by a computer system, cause the computer system to perform the method steps of any of claims 1 to 18.

20. An apparatus for determining a repair shape (195, 295, 395) for processing at least one defect (140, 240) of a lithography mask (100), the apparatus having:

a. a measurement unit implemented to determine the repair shape (145);

b. a calculation unit implemented to determine at least two locally spatially dependent correction values (185, 285, 385) of a repair shape (195, 295, 395) for the at least one defect (140, 240), wherein the at least two locally spatially dependent correction values are different values, wherein:

(i) The at least two locally spatially dependent correction values (185) take into account a position of at least one pattern element (130) of the lithographic mask (100), the at least one pattern element not contacting the at least one defect (140);

(ii) The at least two locally spatially dependent correction values (185) take into account a lateral extent (180) of the at least one defect (140) on the surface of the substrate (110) of the lithographic mask (100); and/or

(iii) The at least two locally spatially dependent correction values (285, 385) take into account a form of at least one pattern element (120, 220) of the lithography mask (100), the at least one pattern element contacting the at least one defect (140, 240); and wherein

c. The calculation unit is further operative to correct the repair shape (195, 295, 395) by applying the at least two locally spatially correlated correction values (185, 285, 385).

21. The apparatus of claim 20, implemented to perform the method steps of any one of claims 1 to 18.